Two men whose argument apparently sparked the violence at Lone Star College-North Harris are hospitalized under armed guard.

HOUSTON — Three people were shot at a north Houston community college Tuesday in the latest act of gun violence to mar a school campus.

Witnesses and officials said the shooting at Lone Star College's North Harris campus erupted about 12:20 p.m. after an argument between two men in front of the school library.

It was not clear whether one or both of the men were armed, authorities said. Both were hurt and hospitalized under armed guard. Late Tuesday, authorities charged one of them with aggravated assault and identified him as Carlton Berry, 22.

A maintenance worker in his mid-50s was shot in the leg and hospitalized in stable condition. A fourth person, a woman with a student ID card whose connection to the school was unclear, was hospitalized with "medical complications" after the melee, said Harris County acting Sheriff Maj. Armando Tello.

It was unclear what sparked the argument at Lone Star, which has 90,000 students and six campuses, including North Harris with 19,000 students.

"I never thought it would happen here. It's starting to become common," said Ana Coronado, 18, a veterinary student in her second semester. "When I chose that college, I chose it because I felt safe there; I felt comfortable. I don't know what to feel now."

Some students did not recognize the sounds as gunfire.

Daniel Flores, 19, was doing homework when he heard six or seven loud pops.

"I thought it was construction," he said. "Then people started running, and I knew it had to be a shooting."

Pedro Cervantes, 19, a dental hygiene student in his second semester, said there were gangs in the suburban area, mostly Bloods.

"You notice it because of the tats," or gang tattoos, he said, and some gang clothing on campus.

But Cervantes said he hadn't felt unsafe at Lone Star until the shooting. Now, he worries about his safety and the value of his degree.

"I'm paying for this," he said. "I don't want this college to have a bad reputation."

Richard Carpenter, chancellor of the Lone Star College System, said weapons were not allowed on campus.

Training had begun for staff last week on how to handle a school shooting, he said. As a result, many workers locked their doors and stayed put after the shots rang out.

"I'm relieved that we were as prepared as we were," Carpenter said. "Often people pass on that training. They say, 'Oh, that won't ever happen here; I don't need that now.' This probably made it very real. I suspect all our employees will be very eager to participate in the future."